Technical Field
The present invention relates to a mold provided with a fine surface roughness thereon, a method for manufacturing the mold and a method for manufacturing a molded product using the mold.
Background Art
Anti-reflective structures having a fine surface roughness, the pitch (or the period) of the fine surface roughness being smaller than the wavelength of light, are used in optical elements. As a method for manufacturing molds for such anti-reflective structures, methods in which a resist undergoes patterning using an interference exposure apparatus or an electron-beam lithography system and then etching or electroforming is carried out are known. However, it is difficult to form a fine surface roughness on a large area of a flat surface or a curved surface by these methods.
Under the above-described situation, the inventors of the present application have developed a method for manufacturing a mold provided with a fine surface roughness thereon by a reactive ion-etching process without the necessity of patterning (Patent document 1). According to the method, a fine surface roughness can be formed on a large area of a flat surface or a curved surface without carrying out patterning.
However, when, for example, a fine surface roughness having a pitch of 0.26 micrometers or less that corresponds to the wavelength equal to less than the minimum wavelength of visible lights is formed, it has been difficult to adjust the shape of the fine surface roughness to a sufficient extent by a reactive ion-etching process alone.
Under the above-described situation, there is a need for a method for manufacturing a mold provided with a fine surface roughness thereon, by which the shape of a fine surface roughness having a pitch in a wide range including a range that is equal to or less than the wavelength of visible light can be adjusted to a sufficient extent and a mold that is manufactured by the method and provided with a fine surface roughness having a shape that has been adjusted to a sufficient extent.